• Title/Summary/Keyword: aerodynamic characteristics

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A study on the Aerodynamic Characteristics of a Flat plat Variable Wing by Combined Swept Back and Forward (평판 가변날개에서 앞-뒤젖힘이 동시에 변할 때의 공력특성에 관한 연구)

  • Lee, B.J.;Oh, S.D.
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.5 no.1
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    • pp.31-50
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    • 1997
  • A new variable wing that can be swept back and forward synchronously were developed to enhance the aerodynamic and stability characteristics of a high speed airplane. The configuration of the new variable wing changes in such a way that inner part of the wing sweeps forward and outer part of the wing sweeps backward, the shift of aerodynamic center of the wing is small, therfore the static margin that is required for the stability of a airplane is not affected. In this study, various configurations of wing models by combined swept back and forward were designed and a wind tunnel tests were conducted to investigate the aerodynamic characteristics of these variable wings. The experimental results showed that the variable wing by combined swept back and forward has no effect on the pitching moment coefficient affecting on an aircraft stability margin and enhance the aerodynamic characteristics for a given approach angle of attack.

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A Comparison of Aerodynamic Characteristics in Muscle Tension Dysphonia and Adductor Spasmodic Dysphonia (근긴장성 발성장애와 내전형 연축성 발성장애의 공기역학적 특성 비교)

  • Heo, Jeonghwa;Song, Kibum;Choi, Yanggyu
    • Phonetics and Speech Sciences
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    • v.5 no.4
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    • pp.63-70
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    • 2013
  • The purpose of this study is to show the aerodynamic characteristics and differences in muscle tension dysphonia and adductor spasmodic dysphonia to predict factors which will provide additional information while preparing for the objective examination standard to distinguish the two dysphonias. Forty-eight individuals diagnosed with muscle tension dysphonia and adductor spasmodic dysphonia participated in this study. PAS was used in order to find the aerodynamic characteristics for the two dysphonias. The outcomes of this study show that the airflow variation and glottal resistance of the two groups showed noticeable differences. This study concludes that the aerodynamic characteristics may be used as additional information on diverse evaluations to classify muscle tension dysphonia and adductor spasmodic dysphonia.

A Study of Unsteady Aerodynamic Characteristics of an Accelerating Aerofoil (가속익의 비정상 공력특성에 관한 연구)

  • Lee, Young-Ki;Kim, Heuy-Dong;Raghunathan, Srinivasan
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.556-561
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    • 2003
  • Flight bodies are subject to highly unstable and severe flow conditions during taking-off and landing periods. In this situation, the flight bodies essentially experience accelerating or decelerating flows, and the aerodynamic characteristics can be completely different from those of steady flows. In the present study, unsteady aerodynamic characteristics of an aerofoil accelerating at subsonic speeds are investigated using a computational method. Two-dimensional, unsteady, compressible Navier-Stokes simulations are conducted with a one-equation turbulence model, Spalart-Allmaras, and a fully implicit finite volume scheme. An acceleration factor is defined to specify the unsteady aerodynamics of the aerofoil. The results show that the acceleration of the subsonic aerofoil generally leads to a variation in aerodynamic characteristics and it is more significant at angles of attack.

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A Study on the Aerodynamic Characteristics of a Joined-wing Aircraft with Variation of Wing Configurations

  • Kidong Kim;Jisung Jang
    • International Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.1-13
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    • 2023
  • The present study was attempted to investigate flow interference effects and the aerodynamic characteristics of the front and rear wings of a joined-wing aircraft by changing the configuration variables. The study was performed using a computational fluid dynamics(CFD) tool to demonstrate forward flight and analyze aerodynamic characteristics. A total of 9 configurations were analyzed with variations on the position, height, dihedral angle, incidence angle, twist angle, sweepback angle, and wing area ratio of the front and rear wings while the fuselage was fixed. The quantities of aerodynamic coefficients were confirmed in accordance with joined-wing configurations. The closer the front and rear wings were located, the greater the flow interference effects tended. Interestingly, the rear wing did not any configuration change, the lift coefficient of the rear wing was decreased when adjusted to increase the incidence angle of the front wing. The phenomenon was appeared due to an effective angle of attack alteration of the rear wing resulting from the flow interference by the front wing configurations.

AERODYNAMIC DESIGN OF A MULTI-FUNCTION AIR DATA SENSOR BY USING CFD AND WIND TUNNEL TEST (전산해석 및 풍동시험을 이용한 다기능 대기 자료 센서의 공력 설계)

  • Park, Y.M.;Choi, I.H.;Lee, Y.G.;Kwon, K.J.;Kim, S.C.;Hwang, I.H.
    • Journal of computational fluids engineering
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    • v.15 no.3
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    • pp.32-38
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    • 2010
  • Aerodynamic design of the vane type multi-function probe was tried by using CFD and wind tunnel test for the MALE UAV and small business jets. The present multi-function probe can measure total pressure, static pressure and angle of attack by using rotating vane. Therefore, major performances are determined by aerodynamic characteristics of vane. In order to design the sensor compatible to the requirement, aerodynamic characteristics of sensors were investigated by using CFD and dynamic response analysis was also performed for transient performance. The final aerodynamic performance was measured by the wind tunnel test at Aerosonic and the results were compared with the present design. The results showed that the aerodynamic design using the CFD can be successfully used for the design of vane type multi-function air data sensor.

Static Characteristics and Design of Hemispherical Aerodynamic Bearing (반구형 공기동압베어링의 정적 특성 및 설계)

  • 김승곤;김준영;최환영
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.10a
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    • pp.217-224
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    • 1997
  • Static characteristics of hemispherical aerodynamic bearing is studied theoretically. In this paper nonlinear equation of second order considering compressibility and slip effect of air is calculated by Newton-Raphson method. Results indicate that axial load capacity has maximum value when the inclination angle of groove is about 30$\circ$, the ratio of groove clearance to ridge clearance is two. We also present the design method of hemispherical Aerodynamic bearing based on it's load capacity taking into account manufacturing and assembling viewpoint.

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Numerical Analysis of Aerodynamic Characteristics and Performance Analysis on H-rotor with Various Solidities (솔리디티에 따른 H-로터의 공기역학적 특성 및 성능해석)

  • Joo, Sungjun;Lee, Juhee
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.6
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    • pp.5-13
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    • 2016
  • Three-dimensional unsteady numerical analysis has been performed to observe aerodynamic characteristics of a H-rotor. Generally, the structure of the H-rotor is simple but the aerodynamic characteristics are exceptionably complicated since the angle of attacks and incident velocities to a blade are considerably varied according to the azimuth angles and solidities. The blade in the upwind revolution between 0 to 180 degree obtains aerodynamic energy from the free stream but the blade in the downwind revolution between 180 to 360 degree does not. When the rotating speed increases, the blade in the downwind revolution accelerates the air around the blade like a fan and it consumes the energy and shows negative torque in the area. On the other hand, the direction of the free stream is bent because of the interaction between blade the free stream. Therefore, the operation point (highest power coefficient) appears at a lower tip-speed-ratio what it is expected.

Study of an AI Model for Airfoil Parameterization and Aerodynamic Coefficient Prediction from Image Data (이미지 데이터를 이용한 익형 매개변수화 및 공력계수 예측을 위한 인공지능 모델 연구)

  • Seung Hun Lee;Bo Ra Kim;Jeong Hun Lee;Joon Young Kim;Min Yoon
    • Journal of the Korean Society of Visualization
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    • v.21 no.2
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    • pp.83-90
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    • 2023
  • The shape of an airfoil is a critical factor in determining aerodynamic characteristics such as lift and drag. Aerodynamic properties of an airfoil have a decisive impact on the performance of various engineering applications, including airplane wings and wind turbine blades. Therefore, it is essential to analyze the aerodynamic characteristics of airfoils. Various analytical tools such as experiments, computational fluid dynamics, and Xfoil are used to perform these analyses, but each tool has its limitation. In this study, airfoil parameterization, image recognition, and artificial intelligence are combined to overcome these limitations. Image and coordinate data are collected from the UIUC airfoil database. Airfoil parameterization is performed by recognizing images from image data to build a database for deep learning. Trained model can predict the aerodynamic characteristics not only of airfoil images but also of sketches. The mean absolute error of untrained data is 0.0091.

AERODYNAMIC ANALYSIS ON LEADING-EDGE SWEEPBACK ANGLES OF FLYING-WING CONFIGURATIONS (전익기 형상의 앞전후퇴각 변화에 따른 공력해석)

  • Lee, J.M.;Chang, J.W.
    • Journal of computational fluids engineering
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    • v.11 no.4 s.35
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    • pp.48-55
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    • 2006
  • A computational study was carried out in order to investigate aerodynamic characteristics on leading edge sweepback angles of Flying-Wing configurations. The viscous-compressible Navire-Stokes equation and Spalart-Allmaras turbulence model of the commercial CFD code were adopted for this computation analysis. This investigation examined aerodynamic characteristics of three different types of leading edge sweepback angles: $30^{\circ}C,\;35^{\circ}C\;and\;40^{\circ}C$. The freestream Mach number was M=0.80 and the angle of attack ranged from ${\alpha}=0^{\circ}C\;to\;{\alpha}=20^{\circ}C$. The results show that the increases in sweepback angle of the Flying-Wing configuration creates more efficient aerodynamic performance.

A Study about aerodynamic characteristics of High speed train by fore-body shape design (고속전철의 형상에 따른 공력특성 연구)

  • 진원재;이봉래
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.735-738
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    • 1997
  • The aerodynamic charateristics of high speed train can be improved by fore-body design. In this paper, the design a fore-body shape which has optimal aerodynamic charateristics, 6 models of fore-body shape are proposed and the change of aerodynamic characteristics is studied through calculations of flow field around high speed train fro each fore-body shape. The flow field around high speed trains are calculated using Navier-Stokes equation. The variational trends of aerodynamic characteristics are studied from the result of flow calculation around high speed trains for 6 fore-body shapes.

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